120 - Steve Fleming and Nadine Dijkstra: Distinguishing Imagination from Reality
Oct 26, 2023
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Prof. Steve Fleming and Dr. Nadine Dijkstra explore the distinction between reality and imagination, discussing a recent study on perceptual reality monitoring. They delve into the role of signal strength in distinguishing reality from imagination and discuss the implications for mental health and court cases. They also share their personal journeys in science and emphasize the importance of perseverance in scientific research.
Our perceptions of reality and imagination can become mixed, and the strength of the signal plays a crucial role in determining our experience.
The study identified three key brain regions involved in distinguishing between reality and imagination: the pre-supplementary motor cortex, the anterior insula, and the right dorsolateral prefrontal cortex.
Deep dives
The Overlapping Perceptions of Reality and Imagination
In this podcast episode, Professor Steve Fleming and Dr. Nadina Dykstra discuss a recent study that challenges the assumption that we can readily distinguish between reality and imagination. They explain that when we internally generate a visual experience, similar brain areas become active as when we actually experience it in reality. The study conducted by Mary C. Wesperger, back in the 19th century, indicated that people can sometimes mistake or confuse their imagination with reality. Building on that study, Dr. Dykstra and Professor Fleming conducted a modern version of the experiment. The results suggest that our perceptions of reality and imagination can become mixed, and that the strength of the signal plays a crucial role in determining our experience. This finding has important implications for understanding consciousness and how we interpret our experiences.
Investigating the Distinction Between Reality and Imagination
The study conducted by Dr. Dykstra and Professor Fleming aimed to investigate how well we can distinguish between reality and imagination. They designed an experiment that involved participants imagining specific stimuli and then presenting them with either the same stimulus or a different one. The three hypotheses they tested were: the null hypothesis, which assumes complete distinction between reality and imagination; the broken model hypothesis, which suggests that perceiving the same stimulus as imagining it leads to mistaking perception for imagination; and the signal strength hypothesis, which posits that our experience is influenced by the strength of the signal, whether it is perceived or imagined. The results of the study aligned with the signal strength hypothesis, indicating that when participants imagined the same stimulus they were presented with, they were more likely to perceive it as real.
The Brain Regions and Neural Correlates of Perception and Imagination
The study also explored the neural correlates of perception and imagination. The researchers identified three key brain regions: the pre-supplementary motor cortex, the anterior insula, and the right dorsolateral prefrontal cortex. These regions were found to be involved in the perception and vividness of both real and imagined stimuli. The correlations observed between brain activity in these regions and participants' ratings of vividness and perceptual visibility suggest that these areas play a role in distinguishing between reality and imagination. However, further research is needed to fully understand the mechanisms at play in these brain regions.
Implications for Mental Health and Reliability of Testimony
The findings of the study have implications for mental health and the reliability of testimony. The research suggests that our perception of reality is subjective and influenced by various factors, including our beliefs, expectations, and motivations. This can have implications for conditions such as hallucinations and psychosis, where the threshold for distinguishing between reality and imagination may be altered. Additionally, the study raises questions about the reliability of eyewitness testimony and the accuracy of our perceptions. Further research is needed to explore these implications and their practical applications.
This week, Julia chats with two guests from University College London, Professor Steve Fleming and Dr. Nadine Dijkstra. Professor Fleming is the Wellcome Trust/Royal Society Sir Henry Dale Fellow at the Department of Experimental Psychology and Principal Investigator at the Wellcome Centre for Human Neuroimaging where he leads the Metacognition Group. He has received numerous awards for his work, including the William James prize from the Association for Scientific Study of Consciousness. Dr. Dijkstra is a Senior Research Fellow at the Wellcome Centre for Human Neuroimaging at University College London. She earned her PhD in Artificial Intelligence at the Donders Institute in 2019, after which she moved to London to pursue a postdoc at UCL with Professor Fleming.
In this episode, Dr. Dijkstra and Professor Fleming take us into the fascinating realm of how we distinguish, or at least attempt to distinguish, reality from imagination. They relate the details of a recent study, which indicates that our perceptions of reality might not be as different from our imaginations as we would like to believe. They suggest that this framework of perceptual reality monitoring could be a lens through which our brains interpret all of our experiences. In fact, this perceptual reality monitoring framework might provide an explanation of how we consciously experience the world. After discussing their recent experiment and relating it to the broader field of consciousness science, each of them shares details about their career journeys and their hopes for the future of the field.
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